Search Results

You are looking at 1 - 3 of 3 items for

  • Author or Editor: Gregory J. McRae x
  • Refine by Access: All Content x
Clear All Modify Search
William R. Goodin
,
Gregory J. McRae
, and
John H. Seinfeld

Abstract

An objective analysis procedure for generating mass-consistent, urban-scale three-dimensional wind fields is presented together with a comparison against existing techniques. The algorithm employs terrain following coordinates and variable vertical grid spacing. Initial estimates of the velocity field are developed by interpolating surface and upper level wind measurements. A local terrain adjustment technique, involving solution of the Poisson equation, is used to establish the horizontal components of the surface field. Vertical velocities are developed from successive solutions of the continuity equation followed by an iterative procedure which reduces anomalous divergence in the complete field. Major advantages of the procedure are that it is computationally efficient and allows boundary values to adjust in response to changes in the interior flow. The method has been successfully tested using field measurements and problems with known analytic solutions.

Full access
William R. Goodin
,
Gregory J. McRae
, and
John H. Seinfeld

Abstract

No abstract available.

Full access
Gregory J. McRae
,
Fredrick H. Shair
, and
John H. Seinfeld

Abstract

This paper describes the results of an atmospheric tracer study in which sulfur hexafluoride (SF6) was used to investigate the transport and dispersion of effluent from a power plant located in a coastal environment. The field study demonstrated that material emitted into an elevated stable layer at night can be transported out over the ocean, fumigated to the surface, and then he returned at ground level by the sea breeze on the next day. At night when cool stable air from the land encounters the warmer ocean convective mixing erodes the stable layer forming an internal boundary layer. When the growing boundary layer encounters an elevated plume the pollutant material, entrained at the top of the mixed layer, can be rapidly transported in ∼20 min to the surface. Various expressions for the characteristic downmixing time (λ = Z i/w *) are developed utilizing the gradient Richardson number, the Monin-Obukhov length and turbulence intensifies. Calculations using these expressions and the field data are compared with similar studies of convective mixing over the land.

Full access